Microsoft Internet Explorer users are at least four times as likely to click on Web ads than Firefox users, according to Adtech AG. During October and November only 0.11% of Firefox users ever clicked on an ad, compared to around 0.5% of IE users. The%age of IE users clicking on ads varied across different versions, with 0.53% of version 5.5 users and 0.44% of version 6.x users clicking on ads. The survey was based on 1,000 web sites across Europe which use Adtech’s ad server.